JP2010168631A - Method for estimating low-temperature reduced powderizing of sintered ore - Google Patents
Method for estimating low-temperature reduced powderizing of sintered ore Download PDFInfo
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本発明は、鉱石系原料である焼結鉱の高炉内における低温還元粉化の評価方法に関するものであり、特にJISに規定される低温還元粉化評価方法を、高炉の実操業に即し、その最適化を図ろうとするものである。 The present invention relates to an evaluation method for low-temperature reduction powdering in a blast furnace of sintered ore that is an ore-based raw material, and in particular, a low-temperature reduction powdering evaluation method specified in JIS, in line with the actual operation of the blast furnace, We intend to optimize that.
鉄鉱石から銑鉄を取り出すための炉である高炉の安定操業において、シャフト部の通気確保はたいへん重要である。しかし、シャフト上部において、焼結鉱が低温還元粉化した場合、発生した粉がシャフト部の通気を阻害する。そのため、従来より、焼結鉱の低温還元粉化を管理する指標として、JIS-RDI試験（JIS M 8720：2001年、以下年は省略する）が使用されている。 In the stable operation of a blast furnace, which is a furnace for extracting pig iron from iron ore, it is very important to ensure the ventilation of the shaft section. However, when the sintered ore is reduced to a low temperature powder at the upper part of the shaft, the generated powder inhibits ventilation of the shaft part. Therefore, the JIS-RDI test (JIS M 8720: 2001, the following years are omitted) has been used as an index for managing low-temperature reduced powdering of sintered ore.
上述したJIS-RDI試験の還元条件は、焼結鉱粒径：16〜19mm、焼結鉱重量：500g、還元温度：550℃、還元時間：30分、還元ガス組成は、CO:CO2:N2＝30：０：70であり、CO：CO2に注目すれば、100：０である。その後、ドラム試験と呼ばれる所定径の筒による回転粉化が行われ、ついで篩分を行い、2.8mm角の網を通過したもの（以下-2.8mmとする）の割合を測定し、その値がJIS-RDI値となる。 The reduction conditions of the JIS-RDI test described above are as follows: sintered ore particle size: 16 to 19 mm, sintered ore weight: 500 g, reduction temperature: 550 ° C., reduction time: 30 minutes, reducing gas composition is CO: CO 2 : N 2 = 30: 0: 70, and focusing on CO: CO 2 , it is 100: 0. After that, rotating powdering with a cylinder of a predetermined diameter called a drum test was performed, followed by sieving and measuring the ratio of what passed through a 2.8mm square net (hereinafter referred to as -2.8mm), and the value was JIS-RDI value.
ここで、JIS-RDI試験条件と高炉内温度・ガス測定結果を図１に示す。図中、●印の位置がJIS-RDIの温度および雰囲気である。一方、(1)BF(RAR:445)は、還元剤比445kg/t・時の高炉内ガス組成、(2)BF(RAR:452)は、還元剤比452kg/t・時の高炉内ガス組成、(3)BF(RAR:486)は、還元剤比486kg/t・時の高炉内ガス組成、を表していて、いずれも雰囲気中にCO2が含まれている。同図から明らかなように、JIS-RDI試験のガス組成は、550℃における高炉内ガス組成と大きく異なっている。そのため、このJIS-RDI値では、正確に高炉内における低温還元粉化を評価することは難しいと考えられる。 Here, JIS-RDI test conditions and blast furnace temperature / gas measurement results are shown in FIG. In the figure, the position marked with ● is the JIS-RDI temperature and atmosphere. On the other hand, (1) BF (RAR: 445) is the gas composition in the blast furnace at a reducing agent ratio of 445 kg / t · h, and (2) BF (RAR: 452) is the gas in the blast furnace at a reducing agent ratio of 452 kg / t · h. The composition, (3) BF (RAR: 486), represents the gas composition in the blast furnace with a reducing agent ratio of 486 kg / t · h, both of which contain CO 2 in the atmosphere. As is clear from the figure, the gas composition of the JIS-RDI test is significantly different from the gas composition in the blast furnace at 550 ° C. Therefore, with this JIS-RDI value, it is considered difficult to accurately evaluate low-temperature reduced powdering in the blast furnace.
そこで、特許文献１および２には、高炉操業計画や原料鉄鉱石の性状の変動に対応し、各々の変動に応じたJIS-RDI上限管理値の決定方法が提案されている。同じく、特許文献３には、高炉内の所定位置における温度およびガス組成を測定し、この温度およびガス組成の測定結果に基づいて高炉中のヘマタイトの減少量を求め、高炉内における焼結鉱の還元粉化量を推定する方法が提案されている。さらに、特許文献４には、微粉炭吹込み高炉操業条件下における焼結鉱の還元粉化温度域での滞留時間および雰囲気ガスの還元ポテンシャルを正確に評価することで、まず、還元試験条件を設定し、その条件を用いて低SiO2焼結鉱の還元粉化性を評価するという方法が示されている。 Therefore, Patent Documents 1 and 2 propose a method for determining a JIS-RDI upper limit management value corresponding to each change in response to changes in the properties of the blast furnace operation plan and raw iron ore. Similarly, in Patent Document 3, the temperature and gas composition at a predetermined position in the blast furnace are measured, and the amount of hematite in the blast furnace is determined based on the measurement results of the temperature and gas composition. A method for estimating the amount of reduced powder is proposed. Furthermore, in Patent Document 4, by accurately evaluating the residence time in the reduced pulverization temperature range of the sintered ore and the reduction potential of the atmospheric gas under the pulverized coal injection blast furnace operating conditions, He sets, the method is shown of evaluating reduction degradation of the low SiO 2 sinter with the condition.
しかし、特許文献１および２では、焼結鉱銘柄による還元粉化量の差を検出することが非常に煩雑でかつ困難という問題があった。 However, Patent Documents 1 and 2 have a problem that it is very complicated and difficult to detect the difference in the amount of reduced powder due to the sintered ore brand.
また、特許文献３の高炉内の所定位置の温度およびガス組成に基づいて、ヘマタイト減少量を求める方法については、ある焼結鉱種における、各位置の実際の還元粉化量の大小は検出できるが、別の焼結鉱種による還元粉化量の差は推定できないという問題があった。
さらに、特許文献４の微粉炭吹込み高炉操業条件下における焼結鉱の還元粉化温度域での滞留時間および雰囲気ガスの還元ポテンシャルを正確に評価して還元条件を設定する方法は、その対象が低SiO2含有焼結鉱であり、高炉の操業条件もパラメータとして影響するため、結果として操業条件ごとの試験が必要となるという問題があった。
つまり、特許文献３および４に示された発明においては、各々の還元試験条件を、個別に設定しなければならず、高炉による連続製造時等では、適切なタイミングで、評価結果を反映させることができないという問題があった。
Moreover, about the method of calculating | requiring the amount of hematite reduction | decrease based on the temperature and gas composition of the predetermined position in the blast furnace of patent document 3, the magnitude of the actual reduction | restoration powder amount of each position in a certain sintered ore type | mold can be detected. However, there is a problem that the difference in the amount of reduced powder by different sintered ore types cannot be estimated.
Further, the method of accurately evaluating the residence time in the reduced pulverization temperature range of sintered ore and the reduction potential of the atmospheric gas under the pulverized coal injection blast furnace operating conditions of Patent Document 4 Is a low SiO 2 containing sinter, and the operating conditions of the blast furnace are also affected as parameters, and as a result, there is a problem that a test for each operating condition is required.
In other words, in the inventions disclosed in Patent Documents 3 and 4, each reduction test condition must be set individually, and the evaluation results should be reflected at an appropriate timing during continuous production using a blast furnace. There was a problem that could not.
本発明は、上述した現状に鑑み、従来のJIS評価方法では困難であった焼結鉱銘柄の違いによる粉化率の差を検出可能とし、さらに、操業に応じた試験条件の変更を行う必要のない統一還元試験条件を用いて、高炉内における焼結鉱の還元粉化量を正確に評価する方法を提供することを目的とする。 The present invention makes it possible to detect the difference in the pulverization rate due to the difference in sintered ore brands, which has been difficult with the conventional JIS evaluation method in view of the above-described current situation, and further, it is necessary to change the test conditions according to the operation. An object of the present invention is to provide a method for accurately evaluating the amount of reduced powdered sinter in a blast furnace using unified reduction test conditions.
以下、本発明の解明経緯について説明する。
発明者らは、まず、JIS-RDI値の決定因子につき考察をした。その結果、図２に示すように、JIS-RDI値と還元率には明確な相関が認められた。これにより、JIS-RDI値は、前述したJIS-RDI試験条件における還元率で決定しているものと考えられる。そこで、JIS-RDI値の異なる3種類の焼結鉱を用い、還元率が低温還元粉化に及ぼす影響を調査した。図３に、この調査に用いた還元装置を示す。図中、１ははかり（balance）、２はエアシリンダ（Air Cylinder）、３はロードセル（Load cell）、４は排気ガス分析（Exhaust gas analysis）、５は熱電対（Thermocouple）、６は試料（Sample）、７はアルミナボール（Alumina ball）、８は電気ヒータ（Electric heater）である。
The elucidation process of the present invention will be described below.
The inventors first considered the determinants of the JIS-RDI value. As a result, as shown in FIG. 2, a clear correlation was recognized between the JIS-RDI value and the reduction rate. Thereby, it is considered that the JIS-RDI value is determined by the reduction rate under the JIS-RDI test conditions described above. Therefore, using three types of sintered ore with different JIS-RDI values, the effect of the reduction rate on low-temperature reduced powdering was investigated. FIG. 3 shows the reduction device used for this investigation. In the figure, 1 is a balance, 2 is an air cylinder, 3 is a load cell, 4 is an exhaust gas analysis, 5 is a thermocouple, 6 is a sample ( Sample, 7 is an alumina ball, and 8 is an electric heater.
図４の「experiment」の欄にJIS-RDI試験条件と比較した本試験条件を示す。同図に示したとおり、還元管の径(Reduction tube diameter)、試料サイズ(Sample size)、試料質量(Sample mass)および還元温度(Reduction temperature)は、JIS-RDI試験条件に準拠した。また、雰囲気(Reduction gas composition)は、vol％でCO／N2＝30/70およびCO／CO2／N2＝22.5/22.5/55とし、時間(Reduction time)を15,30,39,57および90分の5水準とした。さらに、図５に本試験に用いた原料(sample)の性状を示す。 The “experiment” column in FIG. 4 shows the test conditions compared with the JIS-RDI test conditions. As shown in the figure, the reduction tube diameter, the sample size, the sample mass, and the reduction temperature were in accordance with JIS-RDI test conditions. The atmosphere (Reduction gas composition) is CO / N 2 = 30/70 and CO / CO 2 / N 2 = 22.5 / 22.5 / 55 in vol%, and the reduction time is 15, 30, 39, 57 And 5/90 levels. Further, FIG. 5 shows the properties of the raw material (sample) used in this test.
ついで、JIS-RDI試験条件に準じて、ドラムテストおよび篩分テストを行った。上記のCO2混合条件で得られた-2.8mm(screen size)分率をRDI´値とする。
図６に還元率とRDI値およびRDI´値との関係を示す。JIS-RDI試験条件であるCO還元については、還元率4.5％までは還元の進行と共にRDI値は増加するが、還元率4.5％以降はRDI値が一定となる結果が得られた。
Next, a drum test and a sieving test were performed according to the JIS-RDI test conditions. The -2.8 mm (screen size) fraction obtained under the above CO 2 mixing conditions is defined as the RDI ′ value.
FIG. 6 shows the relationship between the reduction rate, the RDI value, and the RDI ′ value. Regarding CO reduction, which is a JIS-RDI test condition, the RDI value increased with the progress of reduction up to a reduction rate of 4.5%, but the RDI value became constant after the reduction rate of 4.5%.
これに対し、高炉内条件に準じたCO＋CO2還元雰囲気においては、2.5％以降はRDI´値が一定となった。このことから、550℃等温還元において、CO還元の場合は還元率4.5％、CO2還元の場合は還元率2.5％に到達すると還元粉化が終了することとなる。この結果より、高炉内における還元粉化率を正しく評価するためには、それぞれの平衡還元率まで還元を行う必要があることが分かった。 On the other hand, in a CO + CO 2 reducing atmosphere according to the blast furnace conditions, the RDI ′ value became constant after 2.5%. Therefore, in the isothermal reduction at 550 ° C., the reduction pulverization ends when the reduction rate reaches 4.5% in the case of CO reduction and 2.5% in the case of CO 2 reduction. From this result, it was found that in order to correctly evaluate the reduced powdering rate in the blast furnace, it is necessary to perform reduction to each equilibrium reduction rate.
しかし、従来のJIS-RDI試験条件下での還元率は、図２に示したように２〜６％と幅がある。つまり、従来のJIS-RDI試験条件下では、平衡還元率である4.5％に満たない範囲についても、-2.8mm粉率を測定し評価していることになる。また、図６に示したとおり、同じ還元率でもCO＋CO2還元の方がCO還元よりも還元粉化が促進されることが分かった。
そこで、還元後の焼結鉱を断面観察し、還元ガスが還元挙動に及ぼす影響について調査を行った。ここで、上記にて実施した試験条件は、ヘマタイトがマグネタイトに還元される領域である。また、ヘマタイトは、焼結鉱の組織中に出現する鉱物のうちで最も明るいため、ヘマタイトのみを撮像できるという特性がある。これを利用して、画像処理を行い、ヘマタイト組織を鮮明化して、ヘマタイトの存在位置を特定し、還元挙動を観察した。図7にCO還元後（還元率5.0％）およびCO＋CO2還元後（還元率2.0％）の焼結鉱の断面組織中ヘマタイトを鮮明化した写真を示す。CO還元後の断面組織中ヘマタイトは、中心部に存在している。このことから、この還元反応は、局所的にトポケミカルに進行したものと考えられる。一方、CO＋CO2還元後の断面組織中ヘマタイトは、全体的に分散して存在している。このことから、この還元反応は、広域的に均一反応して進行したものと考えられる。
However, the reduction rate under the conventional JIS-RDI test conditions varies from 2 to 6% as shown in FIG. In other words, under the conventional JIS-RDI test conditions, the -2.8 mm powder rate is measured and evaluated even in a range where the equilibrium reduction rate is less than 4.5%. Further, as shown in FIG. 6, it was found that CO + CO 2 reduction promotes reduced powdering more than CO reduction even at the same reduction rate.
Then, the cross section of the sintered ore after reduction was observed, and the effect of reducing gas on the reduction behavior was investigated. Here, the test conditions implemented above are regions where hematite is reduced to magnetite. Moreover, hematite has the property that only hematite can be imaged because it is the brightest of the minerals that appear in the structure of sintered ore. Using this, image processing was performed, the hematite structure was clarified, the location of hematite was specified, and the reduction behavior was observed. Fig. 7 shows photographs of the hematite in the cross-sectional structure of the sintered ore after CO reduction (reduction rate 5.0%) and after CO + CO 2 reduction (reduction rate 2.0%). Hematite in the cross-sectional structure after CO reduction exists in the center. From this, it is considered that this reduction reaction locally progressed to topochemical. On the other hand, the hematite in the cross-sectional structure after CO + CO 2 reduction is dispersed throughout. From this, it is considered that this reduction reaction proceeded with uniform reaction over a wide area.
以上の観察結果より、焼結鉱は、還元された周辺部にクラックが発生して粉化現象が生じると考えると、CO還元の場合は、局所的な還元しかなされず、CO＋CO2還元の場合は、広域的に還元反応が生じているために、CO還元に比べて粉化が促進されるものと考えられる。
この還元範囲の差は、CO還元とCO＋CO2還元との還元反応の挙動が異なることを示唆しており、粉化の挙動が異なることにもつながっている。従って、高炉内の還元粉化を正しく評価するためには、高炉内条件に沿ったCO＋CO2還元で行った方が有利であることが分かる。さらに、CO＋CO2還元は、還元粉化が飽和するための還元率も低く、かつ、短時間で到達するために、実製造での現実性も高く、その適用効果も大きい。
以上のような知見を得て、本発明を完成させた。
From the above observation results, considering that sinter ore is cracked in the reduced peripheral area and causes a pulverization phenomenon, in the case of CO reduction, only local reduction is achieved, and in the case of CO + CO 2 reduction It is considered that pulverization is promoted compared with CO reduction because of the reduction reaction occurring in a wide area.
This difference in the reduction range suggests that the behavior of the reduction reaction between CO reduction and CO + CO 2 reduction is different, and also leads to the difference in the behavior of powdering. Therefore, it can be seen that in order to correctly evaluate the reduction pulverization in the blast furnace, it is more advantageous to perform the CO + CO 2 reduction in accordance with the blast furnace conditions. Furthermore, CO + CO 2 reduction has a low reduction rate for saturating reduced powder, and since it can be reached in a short time, it has high practicality in actual production and has a large application effect.
Obtaining the above knowledge, the present invention has been completed.
すなわち、上記知見に基づく本発明の要旨構成は次のとおりである。
（１）鉱石系原料である焼結鉱の高炉内における低温還元粉化の評価方法において、該評価方法に用いる還元ガスとしてCO、CO2、およびN2からなる混合ガスを用い、上記COの配合量が10〜80vol％で、かつ上記COと上記CO2が0.4≦CO/(CO＋CO2）≦0.9の範囲を満たすことを特徴とする焼結鉱の低温還元粉化評価方法。
That is, the gist configuration of the present invention based on the above knowledge is as follows.
(1) In a method for evaluating low-temperature reduced pulverization of sintered ore, which is an ore-based raw material, in a blast furnace, a mixed gas composed of CO, CO 2 and N 2 is used as a reducing gas used in the evaluation method, A low-temperature reduced pulverization evaluation method for sintered ore, wherein the blending amount is 10 to 80 vol%, and the CO and the CO 2 satisfy a range of 0.4 ≦ CO / (CO + CO 2 ) ≦ 0.9.
（２）前記評価方法において、還元温度を500〜600℃の範囲とすることを特徴とする前記（１）に記載の焼結鉱の低温還元粉化評価方法。 (2) In the said evaluation method, reduction temperature shall be the range of 500-600 degreeC, The low temperature reduction pulverization evaluation method of the sintered ore as described in said (1) characterized by the above-mentioned.
本発明は、焼結鉱の低温還元粉化現象が飽和するまで短時間で還元を行うことができ、そのため、実製造の高炉内における焼結鉱の低温還元粉化現象により生じる最終粉化量を、安定してより正確に評価することができる。また、最終粉化量から焼結銘柄の品位差を検出することができる。さらに、焼結銘柄の如何にかかわらず共通の還元試験条件で済むので、評価作業の簡便化を図ることができる。 The present invention can perform the reduction in a short time until the low temperature reduction pulverization phenomenon of the sinter is saturated, and therefore, the final pulverization amount caused by the low temperature reduction pulverization phenomenon of the sinter in the actual blast furnace. Can be evaluated stably and more accurately. Further, the quality difference of the sintered brand can be detected from the final powdered amount. Furthermore, since the common reduction test conditions are sufficient regardless of the sintered brand, the evaluation work can be simplified.
以下、本発明を具体的に説明する。
本発明は、JIS M 8720に示された低温還元粉化試験に準ずるものであるが、特に還元雰囲気を、COとN2からCO、CO2、およびN2の混合ガスに変更することが本発明の最も重要なところである。
The present invention will be specifically described below.
The present invention is intended to conform to the low temperature reduction degradation test shown in JIS M 8720, Books to change particularly the reducing atmosphere, the CO and N 2 CO, CO 2, and the mixed gas of N 2 It is the most important part of the invention.
上記した混合ガス成分の内、基本成分であるCOの配合量は10〜80vol％とする。COが10vol％未満の場合は、混合ガスの還元力が小さく、試験時間が長時間となるからである。一方、80vol％を超えると、還元粉化の終了する還元率が高くなりすぎ、本発明の効果が薄れるからである。なお、好ましくは、20〜50vol％である。 Among the mixed gas components described above, the blending amount of CO, which is a basic component, is 10 to 80 vol%. This is because when the CO content is less than 10 vol%, the reducing power of the mixed gas is small and the test time is long. On the other hand, when it exceeds 80 vol%, the reduction rate at which the reduction powdering is completed becomes too high, and the effect of the present invention is diminished. In addition, Preferably, it is 20-50 vol%.
次に、COとCO2について考える。COは、CO2と酸素を介して平衡状態を作る。従って、上記した３元系の混合ガス中の還元能力は、CO/(CO＋CO2)に関係することが分かる。
そこで、本発明のCO/(CO＋CO2)をパラメータとし、以下の試験条件で低温還元粉化試験を実施した。
Next, consider CO and CO 2 . CO creates an equilibrium through CO 2 and oxygen. Therefore, the reduction capability of a mixed gas of ternary systems described above, it is seen that related to CO / (CO + CO 2) .
Therefore, a low-temperature reduction powdering test was performed under the following test conditions using CO / (CO + CO 2 ) of the present invention as a parameter.
本試験に用いる還元試験装置は、従来公知のJIS-RDI試験装置で良く、焼結鉱試料は、A：高RDI焼結鉱、B：中RDI焼結鉱、C：低 RDI焼結鉱、粒径：16〜20mm、重量：500ｇ（＝Ｗinitial）の３種類を用いた。また、還元条件のうちガス組成は、高炉の炉頂のガス組成を参考に、N2：55vol％一定として、残り45vol％で、CO、CO2の値を種々に変化させ、また、還元温度は550℃、還元時間は30分とした。この時、CO/(CO＋CO2)の値は、0.3〜１の範囲で0.1刻みで行った。ついでJIS M 8720に準拠した条件でドラムテストを行い、-2.8mmの粉率を求めた。試験結果を表１に示す。 The reduction test equipment used in this test may be a conventionally known JIS-RDI test equipment, and the sintered ore samples are A: high RDI sintered ore, B: medium RDI sintered ore, C: low RDI sintered ore, Three types having a particle size of 16 to 20 mm and a weight of 500 g (= W initial ) were used. Further, the gas composition of the reducing conditions, referring to the gas composition of the blast furnace top, N 2: a 55 vol% constant, with the remaining 45 vol%, CO, variously changing the values of CO 2, In addition, the reduction temperature Was 550 ° C. and the reduction time was 30 minutes. At this time, the value of CO / (CO + CO 2 ) was in the range of 0.3 to 1 in increments of 0.1. Next, a drum test was performed under the conditions in accordance with JIS M 8720 to obtain a powder ratio of -2.8 mm. The test results are shown in Table 1.
同表に示した結果から、RDI値と実際の試料（RDI´）値とでは、値に差が有り、粉末の焼結鉱種の差による補正をしないと、実製造には使えないことが分かる。
さらに、CO/(CO＋CO2)の値が0.4〜0.9の範囲であればRDI´値は、ガス組成によらず、ほぼ一定となっていることが分かる。特に、CO/(CO＋CO2)の値が0.5〜0.8の場合には、ばらつきがさらに小さいことが分かる。
以上の結果より、本発明のCO/(CO＋CO2)の値は0.4〜0.9とした。より好ましい範囲は0.5〜0.8である。
From the results shown in the table, there is a difference between the RDI value and the actual sample (RDI´) value, and it cannot be used in actual production unless it is corrected by the difference in the sintered ore type of the powder. I understand.
Furthermore, it can be seen that if the value of CO / (CO + CO 2 ) is in the range of 0.4 to 0.9, the RDI ′ value is substantially constant regardless of the gas composition. In particular, it can be seen that when the value of CO / (CO + CO 2 ) is 0.5 to 0.8, the variation is even smaller.
From the above results, the value of CO / (CO + CO 2 ) of the present invention was set to 0.4 to 0.9. A more preferable range is 0.5 to 0.8.
本発明では、CO2ガスを混合することで、焼結鉱の到達還元率を下げることができる。本発明のCO/(CO＋CO2)が0.4〜0.9の範囲では、この到達還元率の値は、2.5±1.2％である。
この到達還元率に到達する手段としては、焼結鉱中のT.FeとFeOの比が予め分かっているものはその値を使用すれば良く、分かっていない場合には、JIS M 8212「鉄鉱石−全鉄定量方法」：2005年、JIS M 8213「鉄鉱石−酸可溶性鉄 (II) 定量方法」：1995年等によって、焼結鉱中のT.FeとFeOの割合を測定し、例えば、還元率2.5％に到達する重量減少量（Ｗ2.5）を計算すれば良い。ついで、還元試験装置に、熱天秤等の試料重量測定器を設置する。還元試験中の焼結鉱重量がＷinitial−Ｗ2.5となったところで、還元試験を終了すれば、安定して目標還元率2.5％を得ることができ、従来法で見られた還元不足による再試験を行う必要はなくなる。
In the present invention, the ultimate reduction rate of the sintered ore can be lowered by mixing the CO 2 gas. When the CO / (CO + CO 2 ) of the present invention is in the range of 0.4 to 0.9, the ultimate reduction rate is 2.5 ± 1.2%.
As a means to reach this ultimate reduction rate, if the ratio of T.Fe and FeO in the sintered ore is known in advance, it is sufficient to use that value. If it is not known, JIS M 8212 “Iron ore Stone-total iron determination method ": 2005, JIS M 8213" Iron ore-acid soluble iron (II) determination method ": 1995, etc., by measuring the ratio of T.Fe and FeO in sintered ore, for example, The weight reduction amount (W 2.5 ) that reaches a reduction rate of 2.5% may be calculated. Next, a sample weight measuring instrument such as a thermobalance is installed in the reduction test apparatus. When the weight of the sintered ore during the reduction test reaches W initial −W 2.5 , if the reduction test is finished, the target reduction rate of 2.5% can be stably obtained. There is no need to conduct the test.
本発明の還元温度は、500〜600℃が望ましい。これは、500℃に満たないと上記した到達還元率に達しないおそれがあるか、仮に達してもその時間は長大となり、製造上でも経済上でも不利となる。一方、600℃を超えると所望の還元反応以外の反応や組織の変態等の現象が現れてくるため好ましくない。
また、還元時間については、特に制限はないが40〜60分程度で十分である。
なお、CO/(CO＋CO2)が高くなると、還元は早く進行するが、粉化が終了する還元率が高くなるため、還元時間が長くなる。一方、CO/(CO＋CO2)が低くなると還元の進行が遅くなるため、還元時間を長く設定する必要がある。
The reduction temperature of the present invention is preferably 500 to 600 ° C. If this temperature is less than 500 ° C., the above-mentioned ultimate reduction rate may not be reached, or even if it is reached, the time will be long, which is disadvantageous in terms of production and economy. On the other hand, when the temperature exceeds 600 ° C., reactions other than the desired reduction reaction and phenomena such as transformation of the structure appear, which is not preferable.
The reduction time is not particularly limited, but about 40 to 60 minutes is sufficient.
Note that when CO / (CO + CO 2 ) increases, the reduction proceeds faster, but the reduction rate at which pulverization ends increases, and therefore the reduction time increases. On the other hand, when CO / (CO + CO 2 ) is low, the progress of the reduction is slow, and therefore the reduction time must be set longer.
従来の評価指標であるJIS-RDI値および本発明により求めたRDI´値と、高炉内の各位置における圧損との関係を図８に示す。
図中(5)、(6)、(7)は、圧損を測定した位置であり、実際は、羽口からそれぞれ、17.68ｍ、19.54ｍ、21.08ｍの距離にある。また圧損は、高炉に標準設置されているシャフト圧力計を用いて測定を行った。
FIG. 8 shows the relationship between the JIS-RDI value, which is a conventional evaluation index, the RDI ′ value obtained by the present invention, and the pressure loss at each position in the blast furnace.
In the figure, (5), (6), and (7) are the positions at which the pressure loss was measured, and are actually at the distances of 17.68 m, 19.54 m, and 21.08 m from the tuyere, respectively. The pressure loss was measured using a shaft pressure gauge installed as standard in the blast furnace.
これらの試験に供した試料は、複数の実製造の焼結鉱を使用し、RDIは、JIS M 8720に従い、RDI´は、CO/(CO＋CO2)=0.5の条件で行った。高炉の主な操業条件は表２に示す。 Samples used for these tests used a plurality of actually manufactured sintered ores, RDI was in accordance with JIS M 8720, and RDI ′ was CO / (CO + CO 2 ) = 0.5. Table 2 shows the main operating conditions of the blast furnace.
図８に示したとおり、JIS-RDI試験で求めた還元粉化量と高炉内圧損の関係については、低JIS-RDI値側で還元粉化量と高炉内圧損の関係が一定となり、還元粉化量が高炉内通気性に及ぼす影響が明確に反映されていないことが分かる。
この結果に対し、本発明により得られたRDI´値は、高炉内のいずれの場所においても明確な相関が得られている。
As shown in Fig. 8, regarding the relationship between the reduced dusting amount obtained in the JIS-RDI test and the pressure loss in the blast furnace, the relationship between the reduced powdering amount and the pressure loss in the blast furnace is constant on the low JIS-RDI value side. It can be seen that the effect of the conversion amount on the blast furnace air permeability is not clearly reflected.
In contrast to this result, the RDI ′ value obtained by the present invention has a clear correlation at any location in the blast furnace.
本発明は、焼結鉱の高炉内における還元粉化量を、高炉内環境を模擬し、正確に評価できるため、高炉操業時の還元粉化量管理として適用することで、安定した高炉操業、ひいては、安定した焼結鉱の品質を確保することができる。 The present invention simulates the environment inside the blast furnace and accurately evaluates the amount of reduced powdered sinter in the blast furnace.By applying it as reduced powdered amount management during blast furnace operation, stable blast furnace operation, As a result, stable quality of the sintered ore can be ensured.
１ はかり
２ エアシリンダ
３ ロードセル
４ 排気ガス分析
５ 熱電対
６ 試料
７ アルミナボール
８ 電気ヒータ
1 Scale 2 Air Cylinder 3 Load Cell 4 Exhaust Gas Analysis 5 Thermocouple 6 Sample 7 Alumina Ball 8 Electric Heater
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| JP2016079500A (en) * | 2014-10-15 | 2016-05-16 | 新日鐵住金株式会社 | Measuring device and measuring method for evaluating reduction degradation |
| JP2020012789A (en) * | 2018-07-20 | 2020-01-23 | 日本製鉄株式会社 | Particle size distribution constant estimation device, particle size distribution constant estimation program and particle size distribution constant estimation method |
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| JP2012247289A (en) * | 2011-05-27 | 2012-12-13 | Jfe Steel Corp | Reduction powdering rate measuring method of ore |
| JP2016079500A (en) * | 2014-10-15 | 2016-05-16 | 新日鐵住金株式会社 | Measuring device and measuring method for evaluating reduction degradation |
| JP2020012789A (en) * | 2018-07-20 | 2020-01-23 | 日本製鉄株式会社 | Particle size distribution constant estimation device, particle size distribution constant estimation program and particle size distribution constant estimation method |
| JP7087766B2 (en) | 2018-07-20 | 2022-06-21 | 日本製鉄株式会社 | Particle size distribution constant estimation device, particle size distribution constant estimation program, and particle size distribution constant estimation method |
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